The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In recent years, for the purpose of a space saving, a weight saving or the like, there has been developed a resin formation and a downsizing of an opponent part to which the gasket is attached.
Accordingly, an enlargement of a tolerance of the opponent part is generated by the resin formation, and it is necessary to make a height of the gasket higher to secure a collapsing margin of the gasket. Further, it is impossible to satisfy a desired filling factor by a conventional circular cross section, due to a limit of a groove width of a installation groove on the basis of the downsizing, and it is necessary to make a width of the gasket installed to the installation groove narrow.
Accordingly, in recent years, as shown in FIG. 6, there is a case where a gasket 101 is supported by being formed in a vertically long cross-sectional shape in which a height is larger than a width (refer to Japanese Utility Model Application Laid-Open No. 6-65662).
However, in the gasket 101 having the vertically long cross-sectional shape, since an attitude is unstable and a strength is weak, when an opposite surface 102 is abutted on an opponent member 105, the gasket 101 is collapsed by a smaller collapsing margin F (a collapsing margin in the case that a slant is generated) than a normal collapsing margin E due to a slant (FIG. 7), so that there is a risk that a sealing performance is lowered (FIG. 8).
As a countermeasure thereof, as shown in FIG. 9, projections 202 for preventing the slant may be provided in some positions on an inner periphery or an outer periphery of the gasket 201. However, if the gasket is downsized and a product volume is small, there is after all a risk of the slant (FIG. 10) since a rigidity of the projection is inferior. Further, if the projection volume is set such as to sufficiently support the slant, a filling factor gets over 100%, and there is generated a risk of squeezing out.
On the other hand, in order to prevent the slant and a buckling and improve the sealing performance, as shown in FIG. 11, there has been provided a gasket 301 which is formed in a square cross sectional shape, is chamfered in an end portion, and is provided with a protruding portion having a collapsing margin with respect to the other member (refer to the Japanese Utility Model Application Laid-Open No. 6-65662).
Further, in order to prevent the slant or the buckling of the gasket, as shown in FIG. 12, there has been provided a structure in which a gasket 401 is formed in a shape having a self-repairing performance (refer to Japanese Patent No. 3346099).
However, since the gaskets 301 and 401 are formed in an asymmetrical shape vertically, there is a problem that it is hard to discriminate vertically and an installing error tends to be generated in the case that the volume is small.
Accordingly, in Japanese Patent Application Laid-Open No. 2005-16621, there is disclosed a technique for preventing the slant and the buckling by a gasket which is formed in a vertically long cross sectional shape in a groove depth direction installed within a installation groove, and meanders in a groove width direction with respect to the linearly extending installation groove.